1. Field of the Invention
When liquid is supplied from a liquid container to an operation unit and is consumed, the liquid is partially wasted without being used for the operation. The present invention relates to a method for detecting quantity of the waste liquid and a liquid discharging apparatus.
2. Description of the Related Art
The hitherto known ink jet printer has a so-called serial type print head, which is shorter than the width of the printed area of a recording sheet and reciprocates in the widthwise direction of the recording sheet to perform printing.
Such an ink jet printer performs nozzle cleaning in order to prevent clogging of ink discharging nozzles and defective printing caused thereby. For the nozzle cleaning, a waste ink receiver and a head cap with an ink sucking mechanism are provided laterally away from the recording sheet. The print head moves to the waste ink receiver to discharge ink thereto in vain. In addition, the print head moves to the ink sucking mechanism to allow ink to be sucked.
Such nozzle cleaning is easily performed by the ink jet printer with a serial type print head. Since the number of nozzles is small, the quantity of ink received by the waste ink receiver is small. Therefore, the waste ink becomes dry easily, and it is not necessary to replace the waste ink receiver regularly.
Recently, a so-called full-line type print head has been provided. It has a length that allows it to cover the entire width of a recording sheet (for example, an A4 recording sheet).
The full-line type print head has a row of ink discharging nozzles having substantially the same length as the width of the printed area of the recording sheet. If an ink jet printer having the full-line type print head performs the above-described nozzle cleaning, the quantity of ink received by the waste ink receiver is greater than that of the ink jet printer having the serial type print head. Therefore, it is necessary to replace the waste ink receiver regularly.
In this case, it is necessary to inform the user of time to replace the waste ink receiver. A technology for informing the user of time to replace the waste ink receiver is disclosed in, for example, Japanese Patent No. 2755791 (p. 1, FIG. 5). In the technology, the accumulated number of times of nozzle clearing operation is counted, and the counted number of times is stored. Before every nozzle clearing operation, the stored number of times is read out, and it is determined whether the waste ink receiver is still capable of accommodating the waste ink to be discharged in the nozzle clearing operation. If the determination is negative, a warning is given to urge the user to replace the waste ink receiver.
However, this technology has a problem in which the structure is complex and the cost is expensive because it is necessary to provide the waste ink receiver with a special sensor for counting the accumulated number of times of nozzle clearing operation.